1. Field of the Invention
The present invention relates generally to the field of filters for extracting impurities from water solutions in aquariums, and more specifically to a replaceable filter element for absorbing proteins, which includes an open-cell polymeric absorbent such as macroporous, cross-linked polystyrene, formed into numerous microspheres and mixed with polished sand to reduce the solution flow rate near the polymeric absorbent so that protein absorption can occur, and contained within a nylon envelope.
2. Description of the Prior Art
There have long been filtration systems in aquariums for removing organic material. This organic material includes proteins remaining from aquatic life waste products, uneaten food and dead plant tissues. In the past these proteins have been removed with devices referred to as protein skimmers. Air is bubbled through a passageway containing aquarium water. The bubbles carry the proteins to the top of the skimmer where they are periodically removed by skimming the surface. A problem with these systems is that they tend to be relatively costly, complicated and requiring frequent maintenance and replacement.
An example of such a system is that of Cole, U.S. Pat. No. 4,988,436, issued on Jan. 29, 1991. Cole teaches a multi-step filtration device including a foam pre-filter for mechanical particle removal, a conventional protein skimmer, and a biological filter containing a medium such as imploded synthetic polyether foam material. Within this medium, so-called helpful bacteria are grown for breaking down ammonia. The biological filter is stated to be an open-cell synthetic foam material such as polyether foam. Water flows freely through the foam, however, leaving little chance for the foam to absorb proteins. Problems with Cole include the need for careful maintenance and substantial complexity and expense.
Conn, U.S. Pat. No. 3,965,007, issued on Jun. 22, 1976, discloses a protein skimmer including a vertical water-carrying outer tube coaxially containing a narrower air-carrying tube. Air is pumped down the narrower tube to the base of the outer tube and then diffused into numerous small bubbles which rise through the water contained in the outer tube. These bubbles gather and carry organic compounds to a container at the water surface, from which these compounds are periodically removed. Conn presents all the problems mentioned above of the typical protein skimmer, including high cost and limited effectiveness.
Pedretti, U.S. Pat. No. 4,863,594, issued on Sep. 5, 1989, combines biological and mechanical filtration. Air is bubbled through an isolated side compartment of an aquarium and carries organic material to an absorption pad, while circulating the solution up and through a gravel bed to provide biological filtration. A problem with Pedretti is that the filtration provided is of only limited efficiency. Other problems are that the apparatus is relatively complex, expensive to manufacture and difficult to assemble.
Willinger, U.S. Pat. No. 3,815,547, issued on Jun. 11, 1974, teaches an aquarium filtering device dividing the aquarium into first and second compartments. The water level in one compartment is maintained higher than the level in the other by means of a pump. The device has a perforated lower portion below both water levels and porous filter material is contained within the lower portion. Gravity causes water to flow from the higher water level compartment to the lower water level compartment through the perforations and the porous filter material. A problem with Willinger is that the device separates off a significant portion of the aquarium, and is probably only marginally effective.
Schatz, U.S. Pat. No. 3,814,254, issued on Jun. 4, 1974, discloses an aquarium cleansing device which includes a perforated false bottom upon which gravel is placed. Water is pumped out of spaces beneath the false bottom, drawing water down through the gravel and perforations. Organic waste matter collects on the gravel and is periodically dislodged and removed by creating a strong, pulsing flow through the gravel. A problem with Schatz is that the protein-absorption ability of ordinary gravel is minimal, and therefore the cleaning action is only marginally effective. The false bottom structure itself would also be relatively expensive and complicated to manufacture and assemble.
Horvath, U.S. Pat. No. 3,734,853, issued on May 22, 1973, teaches a suction cleaner for aquariums wherein aquarium water is drawn from the bottom of the main tank into a separate filter box. This water is deposited onto layers of filter material in the box and is drawn through the material, thereby freeing the water of its impurities. Then a tube extending from a pump into the water below the filter material delivers this cleaned water into the top of the main tank. Horvath presents a good design, but is limited by the effectiveness of the filter material available on the market.
Huckstedt, U.S. Pat. No. 3,669,883, issued on Jun. 13, 1972, discloses still another air bubble, foam-flotation, protein skimming device. Air is drawn into the system through a venturi apparatus. Problems with Huckstedt include, once again, high manufacturing costs, needless complexity and marginal effectiveness.
It is thus an object of the present invention to provide a filter element for removing proteins from aquarium water which is highly effective and efficient.
It is another object of the present invention to provide such a filter element which can be easily replaced.
It is finally an object of the present invention to provide such a filter element which is simple and inexpensive to manufacture.